Engine Disassembly - Onan T260G Service Manual

Engine Disassembly
DlSASSEMBLY/ASSEMBLY
1. Use the proper bearing driver to install front main
When complete engine disassembly is necessary, first
remove all complete assemblies. Individual assemblies 2. Insert rear main bearing in rear bearing plate.
such as fuel pump and carburetor can be disassembled 3. Insert crankshaft, rear bearing plate, and crankshaft
and repaired at another
bearing after coating it with a light film of oil.
4. Install piston and connecting rods.
Suggested Disassembly Order
5. Install camshaft and gear assembly; align crank
gear mark with cam gear mark.
1. Drain crankcase.
2. Disconnect all exhaust lines and electrical lines. cylinder heads.
6. Install valve assemblies, oil pump, oil base, and
3. Remove engine from its mountings and place on a
suitable bench or work stand.
4. Remove all housings, shrouds, blower housings,
etc.
5. Remove flywheel, using a puller. Note position of
chaff screen and venturi when removing to assure
screw hole alignment on reassembly. See page 10-
18 for further information.
6. Remove ignition trigger ring, if engine is equipped
with electronic ignition.
7. Remove the gear cover, being careful to protect the
oil seal from keyway damage.
7. Install breaker point box.
8. Install all accessories such as oil filter, starter, fuel
lines and spark plugs.
9. Install gear cover with oil seal, trigger ring (electronic
ignition only) and flywheel.
10. Set breaker points (if equipped with points) to obtain
proper timing.
11. Check valve clearance.
12. Install all housings and air cleaner.
13. Fill' crankcase with oil.
8. Remove the crank gear, using a gear puller and ring. Operation
9. Remove all accessories such as oil filter, starter,
Start engine and check oil pressure. Run for approxi-
intake manifold, fuel lines, spark plugs, etc.
mately 15 minutes to bring engine to operating temper-
10. Remove breaker point box.
ature. Check for oil leaks, fuel leaks and exhaust leaks.
11.
Remove oil base, oil pump and cylinder heads.
Adjust carburetor and governor for speed and sensitivity.
12. Remove valves, springs, lifters, etc.
13. Remove camshaft and gear assembly.
14. Remove connecting rods and pistons. Testing Compression
15. Remove rear bearing plate, crankshaft, and front The compression tester is used to determine the
bearing. condition of valves, pistons, piston rings and cylinders.
Keep all parts in their respective orders. Keep valve
assemblies together. Return rod caps to their respective
pistons. Analyze the reasons for parts failure.
Suggested Assembly Procedure
Engine assembly is normally the reverse of the dis-
assembly procedure observing proper clearances and
torques. use a torque wrench to assure proper tightness.
Coat the internal engine parts with oil as they are
assembled. After the internal engine parts are ass-
embled, the engine should turn over by hand freely. Use
only genuine Onan parts and special tools when
reassembling your engine.
To check compression:
1. Run the engine until thoroughly warm.
2. Stop engine and remove spark plugs.
3. Remove air cleaner and place throttle and choke in
4. Insert the compression gauge in one spark plug
5. Crank the engine and note the reading.
the wide open position.
hole.
Refer to SPEClFlCATlONS section for compression
pressures. There may be variations due to equipment,
temperature, atmospheric conditions and altitude. These
pressures are for a warm engine at cranking speed
(about 300 rpm).
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